In order that a large volume of time-series data sequentially generated from a large number of sensors, network apparatuses, etc., are transferred over a network at high speed, there is known a technology for collecting a plurality of small chunks of data items and transferring these data items altogether at a time. For example, PTL 1 discloses a technology in which even when a data transfer request is received, the data is not promptly transferred and the transfer is put on hold for a constant period, and when another data transfer request is received within the same period, the data for these data transfer requests are collectively transmitted at a time.